The invention is in the field of combination products derived from solid hydrocarbonaceous and/or solid carbonaceous material with liquid hydrocarbons, particularly the combination of coal with fuel oil, in order to create a combined product that may be used as a fuel. In particular, the invention is in the field of introduction of solid hydrocarbons, such as coal, into fuel oil in order to upgrade the solid hydrocarbon and replace a proportion of the fuel oil.
Coal fines and ultrafines, including microfines are small particles of coal generated from larger lumps of coal during the mining and preparation process. While coal fines retain the same energy potential of coal they are generally considered a waste product as the particulate nature of the product renders it difficult to market and transport. Coal fines are therefore generally discarded as spoil close to the colliery forming large waste heaps that require careful future management in order to avoid environmental contamination or even the threat to human life as demonstrated in the 1966 Aberfan disaster in South Wales.
Nevertheless, coal fines do offer a cheap and plentiful supply of hydrocarbons particularly rich in carbon. It is known to add slurries of coal fines in water to fuel oils in order to upgrade the coal fine product and reduce the cost per unit volume of the blended fuel oil (see for example U.S. Pat. Nos. 5,096,461, 5,902,359 and 4,239,426). However, in its natural state, coal fines typically contain significant levels of ash-forming components that would render it unsuitable for blending directly with fuel oil. Furthermore, the amount of water present in coal fines (ca. 35% by mass or % m) is also undesirable for use in fuel oil. Selecting coal fines with low mineral matter content is one possibility for ameliorating these problems. Suitable coal fines can be manufactured by crushing and grinding seam coal with inherently low mineral matter content (e.g. <5% m), however, this limits quite substantially the types of coal that can be utilised.
There has been previous research into methods of converting coal into liquid hydrocarbon products: these mainly involve solvent extraction of coal at temperatures above 400° C. under pressure in the presence of hydrogen or a hydrogen donor solvent, e.g. tetralin (1,2,3,4-tetrahydronaphthalene). This has led to several pilot scale developments and at least one full-scale operating plant using the Shenhua process at Ejin Horo Banner, Ordos, Inner Mongolia, China. Exploitation of this process involves, however, a very large capital investment and high associated running costs.
Fuel oil is a higher distillate product derived from crude oil. The term “fuel oil” covers a range of petroleum grades having a boiling point higher than that of gasoline products. Typical fuel oils are residual fuel oils (RFOs) and marine fuel oils (MFOs).
Fuel oil is classed as a fossil fuel and is a non-renewable energy source. Furthermore, while crude oil prices are quite volatile the refined products that are obtained therefrom are always relatively expensive. A way in which fuel oil could be blended with a lower cost hydrocarbon source such as coal, to extend the finite reserves of crude oil, and the resultant refined distillate products, would be highly desirable.
These and other uses, features and advantages of the invention should be apparent to those skilled in the art from the teachings provided herein.
U.S. Pat. No. 2,590,733 and DE3130662 refer to use of RFO-coal dispersions for burners/boilers designed for the use of RFO. As for U.S. Pat. Nos. 4,265,637, 4,251,229, 4,511,364, JPS5636589, JPS6348396, DE3130662, U.S. Pat. Nos. 5,503,646, 4,900,429 and JPS2000290673, U.S. Pat. No. 2,590,733 and DE3130662 utilise coarse particle sizes in the pulverised coal range (<200 microns, or <200 μm) or even larger which would not be suitable for passing through fuel filters.
U.S. Pat. Nos. 4,417,901 and 4,239,426 focus on much higher coal loadings: 30-70%.
U.S. Pat. Nos. 5,096,461, 5,902,359, 4,511,364 and JPS2000290673 relate specifically to coal-oil-water dispersions.
U.S. Pat. Nos. 4,389,219, 4,396,397, 4,251,229, JPS54129008 and JPS5636589 include or specify stabilising additives which may move the properties of the resultant fuel oil-coal blend out of specification.
U.S. Pat. No. 4,090,853A and CA 1096620 A1, plus Clayfield, E. et al., Colloil manufacture and application (Fuel, 1981, 60, 865) relate specifically to coarser particles (<500 μm) suspended in fuel oil and water.
U.S. Pat. No. 8,177,867 B2 and Nunez, G. A. et al., Colloidal coal in water suspensions (Energy and Environmental Science, 2010 3(5), 629) relate specifically to colloidal coal-in-water slurries with 20-80% particles<1 micron size.